<!DOCTYPE html>
<html lang='en'>

<head>
    <meta charset='UTF-8'>
    <meta http-equiv='X-UA-Compatible' content='IE=edge'>
    <meta name='viewport' content='width=device-width, initial-scale=1.0'>
    <title>Document</title>
    <script src='../vue.js'></script>
</head>

<body>
    <div id='app'>
        <h1>{{count}}</h1>
        <button @click="add">直接累加</button>
        <button @click="decrement($event)">每次累减</button>
        <button @click="addn($event,3)">每次累加3</button>
    </div>
    <script>
        const vm = new Vue({
            el: '#app',
            data() {
                return {
                    count: 0
                }
            },
            methods:{
                add(){
                    this.count++
                },
                decrement(e){
                    this.count-- 
                },
                addn(e,n){
                    this.count+=n
                },
            }
        })
    </script>
</body>

</html>